Effects of loudspeaker count and layout on the perception of an ambisonic sound scene

Multichannel loudspeaker arrays form the basis for reproducing spatial sound scenes. When reproducing signals in an ambisonic format, the number and placement of loudspeakers must be matched to the ambisonic order to ensure an adequate representation of the acoustic field. However, cost and space constraints often force a trade-off between the number of loudspeakers and the quality of the listening experience. The aim of this study was to assess the extent to which the number and arrangement of loudspeakers affects the accuracy of virtual sound-source localization and the subjective spatial impression expressed on a Mean Opinion Score (MOS) scale. The experiment was conducted in an anechoic chamber using four configurations containing 4 to 10 loudspeakers distributed around the listener. The participants consisted of non-expert listeners. Test signals consisted of one-second bursts of pink noise, repeated twice and presented from eight azimuth angles. For the quality rating, ambisonics sound scenes were rated. FOA was used for both tasks. Participants indicated the perceived source direction by marking a point on an angular dial and rated the spatial impression on a 1–5 MOS scale. The paper presents the dependence of localization errors on the number and configuration of loudspeakers and indicates the influence of each configuration on overall spatial-impression ratings.